I’m wondering if there is a cheat sheet between ImageJ1 API and ImageJ2 API like this one for R and MATLAB? Either class- or method-based comparisons would help a lot to understand ImageJ2! At the moment, it’s really hard to see the relationship or translate between the two.

To be specific, I’m looking for an ImageJ2 equivalent of ij.IJ.getImage() but could not find it.

It may be worthwhile to have a cheat sheet for a few most frequently used methods.

I like the cheat sheet idea! There are many people looking for that I think. Maybe we can create a repository where we collect a list like this? I would also be interested in a cheat sheet for scripting, like comparing IJ1 / IJ2 / groovy scripts…

To answer your specific question: I have not tried it, but there is an ImageDisplayService with a getActiveDataset() function. Maybe that works?

Also, I am sorry @kouichi-c-nakamura that I have not had time to respond to your ImageJ-MATLAB questions and issues. It is in my backlog to do so later this summer (after June 11). I know that is small comfort but I wanted to at least let you know, and say thank you for your persistence.

To ensure backwards compatibility, ImageJ2 has been designed to fully integrate into the existing ImageJ user interface. This allows users to keep using ImageJ in familiar ways, while providing the ability to migrate toward more powerful new features...

Also, I am sorry @kouichi-c-nakamura that I have not had time to respond to your ImageJ-MATLAB questions and issues.

I hope you like my ijmshow. But ideally it’s better to be dealt with by IJM.show() by itself.

I had to look in the source code of ImageJ-MATLAB to find that context() method. Sorry it was never documented. The ImageJ-MATLAB project was the start of an ImageJ2-based extensible approach to integrate with MATLAB, but the time investment for the project was limited, and it has not been developed much since 2016, when the primary author left the ImageJ project.

ImageJ2 is fundamentally service driven: you always go through an application context. See this notebook for an overview.